Pad conditioner for conditioning a cmp pad and method of making such a pad conditioner

ABSTRACT

The invention provides a pad conditioner for conditioning a CMP pad. The pad conditioner includes a substrate, a plurality of cavities on the substrate, a bonding agent filling in the cavities, and a plurality of abrasive particles securely placed and fixed in the cavities separately. The cavities are arranged in a regular manner and each cavity is sized such that it can accommodate only one abrasive particle. The cavities may be bowl-shaped or of other shapes. A method of making such a pad conditioner is also disclosed.

BACKGROUND

1. Field of the Invention

The present invention relates to a pad conditioner for dressing orconditioning a CMP pad and a method of making such a pad conditioner,and more particularly to a pad conditioner for conditioning a CMP padand a method of making such a pad conditioner wherein abrasive particlesare evenly distributed on the pad conditioner and securely fixed on asubstrate.

2. Description of the Related Art

In current semiconductor manufacturing processes, as the manufacturingtechnology advances, the line width and die size become smaller, andinterconnections more concentrated and need to be stacked into morelayers. Thus the planarization of the wafer becomes important, andChemical Mechanical Polishing (CMP) is the key technology that providesglobal planarization.

In CMP, a silicon wafer is held by a rotating or moving polishing headand pressed on a rotating polishing pad, and slurry is injected onto thepolishing pad. Besides the micro abrasive particles, the slurry alsocontains acid solution or alkaline solution that is chosen based on thematerial to be polished. For example, since most dielectric materialsare oxides, the selected slurry is usually alkaline solution, and if themetal materials such as tungsten or copper are to be polished, theselected slurry is often acid solution. The polishing pads are commonlymade from polyurethane resin and the polishing pad has a rough surfacewith via holes.

The top of polishing pad holds the abrasive particles, usually by ameans such as fibers. It is very important to keep the top as flexibleas possible to provide necessary friction for holding particles.Therefore, although the majority of debris coming from the polishing ofsilicon wafers, slurry particles and conditioning disk is washed away bywater during the CMP process, a small amount of debris still accumulatesin the via holes of the polishing pad, causing the polishing pad surfaceto glaze or harden, which makes the pad less able to hold the slurryparticles. Thus the removal rate of polishing is decreased, which causesinstability in the CMP process and fast wear-out of the polishing pad.

Hence, a pad conditioner that is capable of removing the debris on thepolishing pad surface and reviving the polishing pad is needed so thatthe process remains stable. Moreover, the pad conditioner must also becapable of distributing the slurry uniformly on the polishing pad sothat the process is more stable.

There are two most common types of conventional pad conditioners:electroplated pad conditioner and alloy-brazed pad conditioner. Theabrasive particles of the electroplated pad conditioner are fixed on itssubstrate by way of electroplating nickel, but the bonding force of suchmechanical locking method is poor and the abrasive particles tend to bedislodged easily and may scratch the wafer being polished. Furthermore,the electroplated layer must cover more than half of each abrasiveparticle in order to engage the abrasive particles to the substrate,therefore the protrusion level of the abrasive particles is limited, andthus the polishing pad cannot be effectively conditioned and the viaholes are stuffed with the debris. Therefore, the current CMP processuses less of the electroplated pad conditioner.

On the other hand, abrasive particles of alloy-brazed pad conditionerare fixed on its substrate by way of alloy brazing, and the bondingforce of such chemical locking method is better, and the abrasiveparticles are harder to dislodge than when the electroplated padconditioner is used. However, there are some disadvantages, one of thembeing uneven distribution of particles on the substrate, which mayresult from the unevenness of spacing between abrasive particles or theunevenness of the level of height where the abrasive particles exist.Both of the unevenness causes the abrasive particles to apply unevenforces to the polishing pad, which in turn will cause the abrasiveparticles that bear bigger force to be wholly dislodged or partlychipped easily, thereby leading to scratching of the wafers. Inaddition, if the spacing between the distributed abrasive particles istoo close, the debris would accumulate easily, and the work efficiencyof the pad conditioner would be reduced. Besides, an excessive amount ofaccumulated debris will easily scratch the wafer once they fall off.Thus, different kinds of alloy-brazed pad conditioners have beenprovided to improve the aforementioned problem.

U.S. Pat. No. 6,368,198 discloses a pad dresser and a method of makingsuch a pad dresser. As shown in FIG. 1, abrasive particles 3 are affixedto a substrate 1 via a brazing alloy sheet 2, and the reason that theabrasive particles 3 can be evenly distributed is due to a template withapertures (not shown) that was used to place the abrasive particles onthe brazing alloy sheet 2 before brazing. Moreover, an anti-corrosivelayer of diamond-like carbon (DLC) 5 can be added thereon by physicalvapor deposition. However, the brazing alloy is molten and flows freelyin the high temperature vacuum furnace. Therefore, the pre-placedabrasive particles could be displaced by the brazing liquid such thatneighboring particles touch each other. The bonding force is decreaseddue to such clustering of abrasive particles. The dislodging of abrasiveparticles would still occur at times.

Therefore, a CMP pad conditioner with evenly distributed and firmlyfixed abrasive particles on its substrate is urgently needed insemiconductor manufacturing technology.

BRIEF SUMMARY OF THE INVENTION

An object of the invention is to provide a pad conditioner for evenlyconditioning a CMP pad, and a method of making such a pad conditioner.

Another object of the invention is to provide a pad conditioner forconditioning a CMP pad, wherein abrasive particles are securely fixed onthe substrate, and a method for making such a pad conditioner.

In this invention, abrasive particles refer to all super-hard crystals,including: natural diamond, synthetic single crystal diamond, syntheticpolycrystalline diamond (PCD), cubic boron nitride (cBN),polycrystalline cubic boron nitride (PcBN), etc.

In this invention, a substrate refers to a base member made of materialsuch as metal, alloy, or ceramic.

In this invention, cavities are for containing and holding the abrasiveparticles, and the cavities can be of any shape, such as hemisphericalshape, bowl shape, cylindrical shape, or conical shape.

In this invention, a bonding agent is any material that is capable ofaffixing the abrasive particles to the substrate, including: metal,alloy, etc.

The invention provides a pad conditioner for conditioning a CMP pad,including: a substrate having a plurality of cavities thereon; a bondingagent filling the plurality of cavities; and a plurality of abrasiveparticles fixed in the plurality of cavities by the bonding agent.Preferably, the cavities are arranged in a regular manner and the sizeof each cavity is such that only one abrasive particle can beaccommodated. The cavities are preferred to be bowl-shaped. The bondingagent affixes the plurality of abrasive particles to the plurality ofcavities by way of brazing.

The aforementioned pad conditioner for conditioning a CMP pad furtherincludes a lubricating layer; the lubricating layer is made of parylene,tungsten carbide/carbon film (WC/C), diamond film, or diamond-likecarbon film (DLC). The lubricating layer can enhance the speed of debrisremoval, reduce the accumulation of debris, and shorten the conditioningtime.

Moreover, the invention provides a method of making a pad conditioningfor conditioning a CMP pad, including: providing a substrate; forming aplurality of cavities on the substrate; filling a bonding agent in theplurality of cavities; placing a plurality of abrasive particles in thebonding agent; and securely fixing the plurality of abrasive particleson the substrate by using the bonding agent. The cavities are regularlyarranged and each cavity is sized such that preferably it can onlyaccommodate one abrasive particle. The cavities are preferablybowl-shaped. The bonding agent bonds the plurality of abrasive particlesto the plurality of cavities by way of brazing.

The aforementioned method of making such a pad conditioner furtherincludes: forming a lubricating layer on the substrate, the bondingagent and the plurality of abrasive particles. The lubricating layer ismade of parylene, WC/C, diamond film, or DLC.

Through the invention, the efficiency and uniformity of the padconditioner are improved, and the life of the polishing pad is extended.Moreover, the invention can enhance the stability of CMP process, reducethe conditioning time, minimize the number and time of equipmentmaintenances, and reduce the generation of scratched wafers, thusenhancing the quality and yield of wafers.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a sectional view of a conventional pad conditioner.

FIG. 2 illustrates a sectional view of a pad conditioner according to afirst embodiment of the invention.

FIG. 3 illustrates a sectional view of a pad conditioner according to asecond embodiment of the invention.

FIG. 4 illustrates a sectional view of a pad conditioner according to athird embodiment of the invention.

FIG. 5 illustrates a sectional view of a pad conditioner according to afourth embodiment of the invention.

FIGS. 6A-6E illustrate a method of making a pad conditioner according toa first embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

A pad conditioner for conditioning a CMP pad and a method of making sucha pad conditioner according to a preferred embodiment of the inventionwill be described below with reference to the drawings, wherein the likereference numerals denote the like components. Please note that theembodiments of the invention described below are for explanatorypurposes and are not limited to the description thereof unless suchlimitation is specified in the embodiments.

Referring to FIG. 2, a sectional view of a pad conditioner according toa first embodiment of the invention is disclosed, wherein a plurality ofabrasive particles 13 are respectively fixed in a plurality offlat-bottom, bowl-shaped cavities 14 on a substrate 11 by a bondingagent 12. In this embodiment, the substrate 11 is made of stainlesssteel SUS 316, and the sizes of the abrasive particles are from about100 μm to about 250 μm, preferably about 130 μm to about 200 μm. Thedepth of the cavities 14 is about 50 μm, which can be adjusted accordingto the sizes of the abrasive particles and the protrusion that theabrasive particles are to be exposed. The diameters of the cavities 14are designed to only accommodate one abrasive particle so that theabrasive particles can be evenly distributed as per the positioning ofthe cavities 14. The cavities 14 are of a bowl shape with flat bottom,which can structurally hold the abrasive particle 13 securely andseparate each abrasive particle completely, so that the abrasiveparticles will not be dislodged easily.

FIG. 3 shows a sectional view of a pad conditioner according to a secondembodiment of the invention. The pad conditioner of this embodimentfurther has a lubricating layer 15 deposited on the pad conditionerdescribed in the first embodiment. The lubricating layer 15 can be madeof diamond, DLC, parylene, or WC/C, and is preferably made of Paryleneor WC/C. Not only is the lubricating layer resistant to acids and basessuch that it adapts to different process conditions, it is also capableof filling and fixing the defects on the surface of the pad conditionerto reduce the friction coefficient, so that the surface of the padconditioner is smooth and the rate of debris removal is enhanced. Thus,during the CMP process, the dislodging of abrasive particles or chippingof partial sharp angles caused by uneven forces due to surface defectsis decreased, and therefore the occurrence of scratching of wafers isminimized.

FIG. 4 shows a sectional view of a pad conditioner according to a thirdembodiment of the invention. The pad conditioner of this embodiment isas the pad conditioner described in the first embodiment with theplurality of cavities 14 being of a cylindrical shape instead ofbowl-shaped.

FIG. 5 shows a sectional view of a pad conditioner according to a fourthembodiment of the invention. The pad conditioner of this embodiment isas the pad conditioner described in the first embodiment with theplurality of cavities 14 being cone-shaped instead of bowl-shaped.

The shape of the cavities of the invention is not limited to the shapesdescribed in the aforementioned embodiments; cavities of other shapesalso can achieve the intended effect of the invention.

FIGS. 6A-6E illustrate a method of making the pad conditioner asdescribed in the first embodiment. As shown in FIG. 6A, a substrate 11is provided, and then a photo-resist layer 16 is formed on the substrate11. A pre-defined pattern (not illustrated) is used to expose anddevelop the photo-resist layer 16 to get a patterned photo-resist layer16 a, as shown in FIG. 6B. Referring to FIG. 6C, a plurality ofbowl-shaped cavities 14 are formed on the substrate 11 by wet-etchingand the photo-resist layer 16 a is removed. The cavities 14 are thenfilled with a bonding agent 12 as shown in FIG. 6D by printing method,and then as shown in FIG. 6E, a plurality of abrasive particles 13 arerespectively placed in the bonding agent 12. By way of vacuum brazing,the abrasive particles 13 are securely and separately fixed on thesubstrate 111 by the bonding agent 12.

In the method of making such a pad conditioner of the invention, the wayto form cavities is not limited to wet-etching; other methods such asmechanical drilling, laser drilling, galvanic process, dry-etching, andmore, can be used.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. In other words, it is intendedto include equivalent modifications and changes of the above embodimentswithout departing from the spirit and scope of the invention as would beapparent to those skilled in the art. Therefore, the scope of theappended claims should be accorded the broadest interpretation so as toencompass all such equivalent modifications and changes.

1. A pad conditioner for conditioning a CMP pad, comprising: a substratehaving a plurality of cavities thereon; a bonding agent filling theplurality of cavities; and a plurality of abrasive particles fixed inthe plurality of cavities by the bonding agent.
 2. The pad conditionerfor conditioning a CMP pad as described in claim 1, wherein theplurality of cavities are arranged in a regular manner.
 3. The padconditioner for conditioning a CMP pad as described in claim 2, whereinthe size of each of the plurality of cavities is such that one cavitycan only accommodate one abrasive particle.
 4. The pad conditioner forconditioning a CMP pad as described in claim 3, wherein the plurality ofcavities are bowl-shaped with a flat bottom, cone-shaped, or of acylindrical shape.
 5. The pad conditioner for conditioning a CMP pad asdescribed in claim 4, wherein the plurality of abrasive particles arefixed in the plurality of cavities with the bonding agent by way ofbrazing.
 6. The pad conditioner for conditioning a CMP pad as describedin claim 1, further comprising: a lubricating layer.
 7. The padconditioner for conditioning a CMP pad as described in claim 6, whereinthe lubricating layer is made of parylene.
 8. The pad conditioner forconditioning a CMP pad as described in claim 6, wherein the lubricatinglayer is made of tungsten carbide/carbon film (WC/C).
 9. A method ofmaking a pad conditioner for conditioning a CMP pad, the methodcomprising: providing a substrate; forming a plurality of cavities onthe substrate; filling the plurality of cavities with a bonding agent;placing a plurality of abrasive particles on the bonding agent in thecavities; and securely and separately fixing the plurality of abrasiveparticles on the substrate by using the bonding agent.
 10. The method ofmaking such pad conditioner as described in claim 9, wherein theplurality of cavities are arranged in a regular manner.
 11. The methodof making such pad conditioner as described in claim 9, wherein the sizeof each of the plurality of cavities is such that one cavity can onlyaccommodate one abrasive particle.
 12. The method of making such padconditioner as described in claim 9, wherein the plurality of cavitiesare bowl-shaped with a flat bottom, cone-shaped, or of a cylindricalshape.
 13. The method of making such pad conditioner as described inclaim 9, wherein the plurality of abrasive particles are fixed in theplurality of cavities with the bonding agent by way of brazing.
 14. Themethod of making such pad conditioner as described in claim 9, furthercomprising: forming a lubricating layer on the substrate, the bondingagent, and the plurality of abrasive particles.
 15. The method of makingsuch pad conditioner as described in claim 14, wherein the lubricatinglayer is made of parylene.
 16. The method of making such pad conditioneras described in claim 14, wherein the lubricating layer is made oftungsten carbide/carbon film (WC/C).
 17. The method of making such padconditioner as described in claim 9, wherein the plurality of cavitiescan be formed by wet-etching, laser drilling, mechanical drilling orgalvanic process.